Celestron (and HomeBrew) WiFi devices have two operation modes: "Direct Connect", where the device broadcasts its own softAP SSID, and "Access Point" mode, where the device connects to an existing WiFi Access Point SSID.
Configuring the SSID and Passkey for "Access Point" mode can be tricky, and this app aims to simplify that.
First, put the device into "Direct Connect" mode, and then connect your smartphone's WiFi to the device's softAP SSID, eg. "Celestron-123" or "HomeBrew-ABCD". One may also need to confirm to the smartphone that it should remain connected, despite having no internet access.
Now run this app, and it should find the device and display its existing WiFi configuration parameters. Edit those as required, typically entering one's home SSID/Passkey in the Access Point section, and then tap "Save".
Now switch the device to Access Point mode, and it should connect to the configured SSID. Also remember to reconnect the smartphone to that same network before trying to run the SkyPortal or SkySafari apps to connect through the device to a telescope mount.